<s>
Deep	B-Protocol
content	I-Protocol
inspection	I-Protocol
(	O
DCI	O
)	O
is	O
a	O
form	O
of	O
network	O
filtering	O
that	O
examines	O
an	O
entire	O
file	O
or	O
MIME	B-Protocol
object	O
as	O
it	O
passes	O
an	O
inspection	O
point	O
,	O
searching	O
for	O
viruses	O
,	O
spam	O
,	O
data	B-General_Concept
loss	I-General_Concept
,	O
key	O
words	O
or	O
other	O
content	O
level	O
criteria	O
.	O
</s>
<s>
Deep	B-Protocol
Content	I-Protocol
Inspection	I-Protocol
is	O
considered	O
the	O
evolution	O
of	O
Deep	B-Application
Packet	I-Application
Inspection	I-Application
with	O
the	O
ability	O
to	O
look	O
at	O
what	O
the	O
actual	O
content	O
contains	O
instead	O
of	O
focusing	O
on	O
individual	O
or	O
multiple	O
packets	O
.	O
</s>
<s>
Deep	B-Protocol
Content	I-Protocol
Inspection	I-Protocol
allows	O
services	O
to	O
keep	O
track	O
of	O
content	O
across	O
multiple	O
packets	O
so	O
that	O
the	O
signatures	O
they	O
may	O
be	O
searching	O
for	O
can	O
cross	O
packet	O
boundaries	O
and	O
yet	O
they	O
will	O
still	O
be	O
found	O
.	O
</s>
<s>
Unlike	O
shallow	O
inspection	O
methods	O
such	O
as	O
Deep	B-Application
Packet	I-Application
Inspection	I-Application
(	O
DPI	O
)	O
,	O
where	O
only	O
the	O
data	O
part	O
(	O
and	O
possibly	O
also	O
the	O
header	O
)	O
of	O
a	O
packet	O
are	O
inspected	O
,	O
Deep	B-Protocol
Content	I-Protocol
Inspection	I-Protocol
(	O
DCI	O
)	O
-based	O
systems	O
are	O
exhaustive	O
,	O
such	O
that	O
network	O
traffic	O
packets	O
are	O
reassembled	O
into	O
their	O
constituting	O
objects	O
,	O
un-encoded	O
and/or	O
decompressed	O
as	O
required	O
,	O
and	O
finally	O
presented	O
to	O
be	O
inspected	O
for	O
malware	O
,	O
right-of-use	O
,	O
compliance	O
,	O
and	O
understanding	O
of	O
the	O
traffic	O
's	O
intent	O
.	O
</s>
<s>
If	O
this	O
reconstruction	O
and	O
comprehension	O
can	O
be	O
done	O
in	O
real-time	O
,	O
then	O
real-time	O
policies	O
can	O
be	O
applied	O
to	O
traffic	O
,	O
preventing	O
the	O
propagation	O
of	O
malware	O
,	O
spam	O
and	O
valuable	O
data	B-General_Concept
loss	I-General_Concept
.	O
</s>
<s>
New	O
generation	O
of	O
Network	O
Content	O
Security	O
devices	O
such	O
as	O
Unified	O
Threat	O
Management	O
or	O
Next	B-Application
Generation	I-Application
Firewalls	I-Application
(	O
Garner	O
RAS	O
Core	O
Research	O
Note	O
G00174908	O
)	O
use	O
DPI	O
to	O
prevent	O
attacks	O
from	O
a	O
small	O
percentage	O
of	O
viruses	O
and	O
worms	O
;	O
the	O
signatures	O
of	O
these	O
malware	O
fit	O
within	O
the	O
payload	O
of	O
a	O
DPI	O
's	O
inspection	O
scope	O
.	O
</s>
<s>
Computer	O
networks	O
send	O
information	O
across	O
a	O
network	O
from	O
one	O
point	O
to	O
another	O
;	O
the	O
data	O
(	O
sometimes	O
referred	O
to	O
as	O
the	O
payload	O
)	O
is	O
‘	O
encapsulated’	O
within	O
an	O
IP	B-Protocol
packet	I-Protocol
,	O
which	O
looks	O
as	O
follows	O
:	O
</s>
<s>
*	O
The	O
IP	O
Header	O
provides	O
address	O
information	O
-	O
the	O
sender	O
and	O
destination	O
addresses	O
,	O
while	O
the	O
TCP/UDP	O
Header	O
provided	O
other	O
pertinent	O
information	O
such	O
as	O
the	O
port	O
number	O
,	O
etc	O
.	O
</s>
<s>
Historically	O
,	O
inspection	O
technology	O
examined	O
only	O
the	O
IP	O
Header	O
and	O
the	O
TCP/UDP	O
Header	O
.	O
</s>
<s>
This	O
scheme	O
of	O
network	O
traffic	O
inspection	O
was	O
first	O
used	O
by	O
firewalls	B-Application
to	O
protect	O
against	O
packet	O
attacks	O
.	O
</s>
<s>
This	O
scheme	O
was	O
first	O
used	O
by	O
Check	O
Point	O
firewalls	B-Application
and	O
eventually	O
Intrusion	O
Prevention/Detection	O
Systems	O
.	O
</s>
<s>
Deep	B-Application
Packet	I-Application
Inspection	I-Application
is	O
currently	O
the	O
predominant	O
inspection	O
tool	O
used	O
to	O
analyze	O
data	O
packets	O
passing	O
through	O
the	O
network	O
,	O
including	O
the	O
headers	O
and	O
the	O
data	O
protocol	O
structures	O
.	O
</s>
<s>
To	O
be	O
effective	O
,	O
Deep	B-Application
Packet	I-Application
Inspection	I-Application
Systems	O
must	O
‘	O
string’	O
match	O
Packet	O
Payloads	O
to	O
malware	O
signatures	O
and	O
specification	O
signatures	O
(	O
which	O
dictate	O
what	O
the	O
request/response	O
should	O
be	O
like	O
)	O
at	O
wire	O
speeds	O
.	O
</s>
<s>
Payload	O
limitations	O
:	O
Web	O
applications	O
communicate	O
content	O
using	O
binary-to-text	B-Device
encoding	I-Device
,	O
compression	O
(	O
zipped	O
,	O
archived	O
,	O
etc	O
.	O
</s>
<s>
)	O
,	O
obfuscation	O
and	O
even	O
encryption	B-Protocol
.	O
</s>
<s>
The	O
common	O
workaround	O
is	O
to	O
have	O
signatures	O
be	O
similarly	O
‘	O
encoded’	O
or	O
zipped	O
which	O
,	O
given	O
the	O
above	O
‘	O
search	O
limitations’	O
,	O
cannot	O
scale	O
to	O
support	O
every	O
application	B-Application
type	I-Application
,	O
or	O
nested	O
zipped	O
or	O
archived	O
files	O
.	O
</s>
<s>
Parallel	O
to	O
the	O
development	O
of	O
Deep	B-Application
Packet	I-Application
Inspection	I-Application
,	O
the	O
beginnings	O
of	O
Deep	B-Protocol
Content	I-Protocol
Inspection	I-Protocol
can	O
be	O
traced	O
back	O
as	O
early	O
as	O
1995	O
with	O
the	O
introduction	O
of	O
proxies	O
that	O
stopped	O
malware	O
or	O
spam	O
.	O
</s>
<s>
Deep	B-Protocol
Content	I-Protocol
Inspection	I-Protocol
,	O
can	O
be	O
seen	O
as	O
the	O
third	O
generation	O
of	O
Network	O
Content	O
Inspection	O
,	O
where	O
network	O
content	O
is	O
exhaustively	O
examined	O
,	O
</s>
<s>
These	O
graduated	O
to	O
what	O
is	O
now	O
known	O
as	O
secure	B-Protocol
web	I-Protocol
gateways	I-Protocol
,	O
proxy-based	O
inspections	O
retrieve	O
and	O
scans	O
object	O
,	O
script	O
,	O
and	O
images	O
.	O
</s>
<s>
2006	O
saw	O
the	O
release	O
of	O
the	O
open-source	O
,	O
cross-platform	O
antivirus	O
software	O
ClamAV	B-Application
provided	O
support	O
for	O
caching	O
proxies	O
,	O
Squid	B-Protocol
and	O
NetCache	B-Protocol
.	O
</s>
<s>
Using	O
the	O
Internet	B-Protocol
Content	I-Protocol
Adaptation	I-Protocol
Protocol	I-Protocol
(	O
ICAP	O
)	O
,	O
a	O
proxy	O
will	O
pass	O
the	O
downloaded	O
content	O
for	O
scanning	O
to	O
an	O
ICAP	O
server	O
running	O
an	O
anti-virus	O
software	O
.	O
</s>
<s>
While	O
proxies	O
(	O
or	O
secure	B-Protocol
web	I-Protocol
gateways	I-Protocol
)	O
provide	O
in-depth	O
network	O
traffic	O
inspection	O
,	O
their	O
use	O
is	O
limited	O
as	O
they	O
:	O
</s>
<s>
and	O
finally	O
,	O
proxy	O
architectures	O
which	O
are	O
typically	O
built	O
around	O
Squid	B-Protocol
,	O
which	O
cannot	O
scale	O
with	O
concurrent	O
sessions	O
,	O
limiting	O
their	O
deployment	O
to	O
enterprises	O
.	O
</s>
<s>
The	O
Second	O
generation	O
of	O
Network	O
Traffic	O
Inspection	O
solutions	O
were	O
implemented	O
in	O
firewalls	B-Application
and/or	O
UTMs	O
.	O
</s>
<s>
The	O
third	O
,	O
and	O
current	O
,	O
generation	O
of	O
Network	O
Content	O
Inspection	O
known	O
as	O
Deep	B-Protocol
Content	I-Protocol
Inspection	I-Protocol
solutions	O
are	O
implemented	O
as	O
fully	O
transparent	O
devices	O
that	O
perform	O
full	O
application	O
level	O
content	O
inspection	O
at	O
wire	O
speed	O
.	O
</s>
<s>
In	O
order	O
to	O
understand	O
the	O
communication	O
session	O
's	O
intent	O
—	O
in	O
its	O
entirety	O
—	O
,	O
a	O
Deep	B-Protocol
Content	I-Protocol
Inspection	I-Protocol
System	O
must	O
scan	O
both	O
the	O
handshake	O
and	O
payload	O
.	O
</s>
<s>
Because	O
of	O
the	O
availability	O
of	O
the	O
complete	O
payload	O
's	O
objects	O
,	O
and	O
these	O
schemes	O
of	O
inspection	O
,	O
Deep	B-Protocol
Content	I-Protocol
Inspection	I-Protocol
Systems	O
are	O
typically	O
deployed	O
where	O
high-grade	O
Security	O
and	O
Compliance	O
is	O
required	O
or	O
where	O
end-point	O
security	O
solutions	O
are	O
not	O
possible	O
such	O
as	O
in	O
bring	O
your	O
own	O
device	O
,	O
or	O
Cloud	O
installations	O
.	O
</s>
<s>
This	O
third	O
generation	O
approach	O
of	O
Deep	B-Protocol
Content	I-Protocol
Inspection	I-Protocol
was	O
developed	O
within	O
the	O
defence	O
and	O
intelligence	O
community	O
,	O
first	O
appearing	O
in	O
guard	O
products	O
such	O
as	O
SyBard	O
,	O
and	O
later	O
by	O
.	O
</s>
<s>
The	O
main	O
differentiators	O
of	O
Deep	B-Protocol
Content	I-Protocol
Inspection	I-Protocol
are	O
:	O
</s>
<s>
Deep	B-Protocol
Content	I-Protocol
Inspection	I-Protocol
is	O
Content-focused	O
instead	O
of	O
analyzing	O
packets	O
or	O
classifying	O
traffic	O
based	O
on	O
application	O
types	O
such	O
as	O
in	O
Next	B-Application
Generation	I-Application
Firewalls	I-Application
.	O
</s>
<s>
Because	O
of	O
the	O
availability	O
of	O
the	O
complete	O
objects	O
of	O
that	O
payload	O
to	O
a	O
Deep	B-Protocol
Content	I-Protocol
Inspection	I-Protocol
system	O
,	O
some	O
of	O
the	O
services/inspection	O
examples	O
can	O
include	O
:	O
</s>
<s>
The	O
following	O
patent	O
USPTO#	O
7,630,379	O
provides	O
a	O
scheme	O
as	O
to	O
how	O
Deep	B-Protocol
Content	I-Protocol
Inspection	I-Protocol
can	O
be	O
carried	O
out	O
effectively	O
using	O
a	O
recurrence	O
selection	O
scheme	O
.	O
</s>
